Process for the preparation of isocyanates and their use for the preparation of polyisocyanates containing ester

ABSTRACT

This invention relates to a novel process for the preparation of isocyanates containing silylated alcoholic or phenolic hydroxyl groups as substituents and to the use of the compounds obtained by this process as reactants for isocyanatocarboxylic acid halides in the preparation of polyisocyanates containing ester groups.

BACKGROUND OF THE INVENTION

This invention relates to a novel process for the preparation ofisocyanates containing silylated hydroxyl groups or silylated carboxylgroups as substituents and to the use of the compounds obtained by thisprocess as reactants for isocyanatocarboxylic acid halides in thepreparation of polyisocyanates containing ester groups.

The preparation of organic isocyanates containing silylated alcoholichydroxyl groups as substituents is known. Silyloxyalkyl isocyanates, forexample, are obtained by reaction of the amino alcohols corresponding tothe isocyanates with bis(3-chlorophenyl)carbonate to produceN-(2-hydroxyalkyl)carbamic acid 4-chlorophenyl ester; silylation of thereaction product with trimethylchlorosilane in the presence of anequimolar quantity of triethylamine; and decomposition of the resultingcarbamic acid ester. H. R. Kricheldorf, Liebigs Annalen der Chemie(1973), 772.

The preparation of aromatic isocyanates containing silylated phenolichydroxyl groups as substituents by thermal decomposition of thecorresponding O-phenylurethanes has also been described by H. R.Kricheldorf, see above reference. The ester used for this purpose mustbe prepared from N,O-bis-silylated aminophenols and chloroformic acidphenyl ester in the presence of triethylamine.

Another process for the preparation of isocyanates containing silylatedhydroxyl groups is based on the reaction of trimethylsilyloxybenzoylchloride with trimethylsilyl azide, the isocyanates being formed byCurtius degradation of the acid azides. The process is limited totrimethylsilyloxyaryl isocyanates because trimethylsilyloxyalkanoylchlorides cannot be prepared, G. Schwarz, H. Alberts, H. R. Kricheldorf,Liebigs Annalen der Chemie (1981), 1257.

All of these processes known in the art are cumbersome multistageprocesses that are not generally applicable and that have hitherto beendescribed only in the scientific literature, without significantpractical technology having been demonstrated.

It has now surprisingly been found that organic isocyanates containingsilylated hydroxyl groups or silylated carboxyl groups, preferablyalcoholic or phenolic hydroxyl groups as substituents may easily beobtained by reaction at elevated temperatures of the correspondingO-silylated amino phenols, amino alcohols or aminocarboxylic acids withat least equivalent quantities of non-volatile organic polyisocyantes.The O-silylated starting materials used for this reaction may in turn beobtained by a simple reaction of the corresponding amino phenols, aminoalcohols or aminocarboxylic acids with hexamethyldisilazane (HMDS).

SUMMARY OF THE INVENTION

The present invention relates to a process for the preparation ofisocyanate compounds substituted with one or more silylated hydroxylgroups or silylated carboxyl groups, preferably silylated alcoholic orphenolic hydroxyl groups comprising heating in a temperature range offrom about 20° C. to about 300° C., optionally at reduced pressure, amixture of

(i) amine precursors corresponding to said isocyanate compoundssubstituted with one or more silylated hydroxyl groups or silylatedcarboxyl groups, and

(ii) at least about one to about 20 molar quantities of organicpolyisocyanates that are essentially nonvolatile under the conditions ofthe process.

The products of the process are recovered in the form of the distillateobtained during the course of the reaction.

The amine precursors used as component (i) in the process according tothe invention may be hydroxyl amine or any primary amines that aresubstituted with at least one silylated alcoholic or phenolic hydroxylgroup or at least one silylated carboxylic group and which are suitablefor conversion to corresponding isocyanates. Particularly suitablestarting materials are compounds corresponding to the followingformulas: ##STR1## wherein m is zero or an integer of from 2 to 4.

Suitable O-silylated amino phenols are also those which carry inertsubstituents in the 2-position to the amino group. Possible inertsubstituents are chlorine, bromine, nitro, alkyl groups with 1-20,preferably 1-4 carbon atoms, alkoxy groups with 1-20, preferably 1-4carbon atoms and alkoxy carbonyl groups with 1-20, preferably 1-4 carbonatoms in the alkoxy moiety.

The following, for example, are suitable amine precursors; 2-, 3- and4-(trimethylsilyloxy)aniline, 2-(trimethylsilyloxy)ethylamine,3-(trimethylsilyloxy)propylamine and 4-(trimethylsilyloxy)butylamine.Also suitable are, for example,1-(2-aminoethoxy)-2-trimethylsilyloxyethane,1,1-dimethyl-2-trimethylsilyloxyethylamine, trimethyl siloxy amine,4-(trimethylsiloxy)-cyclohexyl amine, 4-aminobenzoic acidtrimethylsilylester or 2-methyl-4-trimethylsiloxyphenylamine. Thecorresponding compounds in which some or all of the substituents on thesilicon atom are higher alkyl groups, such as ethyl, propyl or butylgroups instead of the methyl group, are also suitable but lesspreferred.

O-Silylated aminophenols and amino alcohols of this type may beprepared, for example, by a method analogous to that described by E.Lukevits et al in Zh. Obshch. Khim, 39, 806 (1969) by monosilylation ofthe amino phenols or amino alcohols using hexaalkyldisilazane,preferably hexamethyldisilazane (HMDS). The reaction may be carried out,for example, by heating the amino phenols or amino alcohols with HMDS inproportions corresponding to a molar ratio of hydroxyl groups to HMDS offrom 1:0.5 to 1:0.6 at temperatures of up to 170° C. (preferably 50° to170° C.) in the presence of a catalytic quantity oftrimethylchlorosilane. Selective silylation of the hydroxyl groups, withconcomitant elimination of ammonia, occurs.

The essentially non-volatile polyisocyanates used as component (ii) inthe process according to the invention are high boiling polyisocyanates.As used herein, the term "high boiling polyisocyanates" includes organicpolyisocyanates that do not boil under the conditions employed for theprocess according to the invention. That is, they are eithernon-distillable polyisocyanates or high boiling polyisocyanates having aboiling point preferably at least 20° C. above the boiling point of theproduct of the process. Any organic polyisocyanates which satisfy theseconditions are suitable in principle but appropriate aromaticpolyisocyanates are preferred. Particularly suitable polyisocyanatesare, for example, the polyisocyanates or polyisocyanate mixtures of thediphenylmethane series, such as 4,4'-diisocyanatodiphenylmethane;mixtures thereof with 2,4'- and, optionally,2,2'-diisocyanatodiphenylmethane; or polyisocyanate mixtures whichcontain higher nuclear polyisocyanates in addition to the above isomers,such as the mixtures obtained from the phosgenation ofaniline-formaldehyde condensates. Aliphatic polyisocyanates, such ashexamethylene diisocyanate or isophorone diisocyanate, are also suitablein principle.

The polyisocyanates (ii) are used in at least equivalent quantities inthe process according to the invention. This means that at least about1, preferably at least 1.1, and more preferably up to 20, isocyanategroups of component (ii) are available for each amino group of component(i). Although an even greater excess of component (ii) could inprinciple be used, the yield would not increase.

DETAILED DESCRIPTION OF THE INVENTION

The process according to the invention may be carried out, for example,by introducing polyisocyanate component (ii) into a suitable reactionvessel equipped with stirrer and distillation bridge and addingcomponent (i) portion-wise with stirring within the temperature range offrom 20° to 300° C., preferably from 20° to 200° C., and more preferablystarting at about 100° to 140° C. and then heating to 200° C. after allof component (ii) has been added. The product of the process, whichforms spontaneously, is then recovered as distillate, optionally undervacuum. Alternatively, components (i) and (ii) may be mixed together ata lower temperature, followed by heating to 200° C., optionally atpressures below atmospheric pressure. The resulting product of theprocess may at the same time be recovered as distillate.

The preferred products of the process according to the inventioncorrespond to the following formulas: ##STR2## wherein m is zero or aninteger of from 2 to 4.

The products of the process according to the invention which carrysilylated alcoholic or phenolic hydroxy groups are valuable intermediateproducts for the preparation of polyisocyanates containing ester groups.These may in turn be used as polyisocyanate components for theproduction of polyurethanes.

For this use according to the invention, said products according to theinvention are reacted with isocyanatocarboxylic acid halides, preferablyisocyantocarboxylic acid chlorides. Suitable isocyanatocarboxylic acidchlorides include compounds corresponding to the following generalformula

    OCN--R--COCl

wherein

R is an aliphatic hydrocarbon group with 1 to 5 carbon atoms or anaromatic hydrocarbon group with 6 to 10 carbon atoms, wherein at least 2carbon atoms are arranged between the isocyanate groups and thechlorocarbonyl group.

Examples of such particularly preferred isocyanatocarboxylic acidchlorides include 3-isocyanatopropionic acid chloride,4-isocyanatobutyric acid chloride, 3-isocyanatobenzoic acid chloride,and 4-isocyanatobenzoic acid chloride.

In addition to these particularly preferred isocyanatocarboxylic acidchlorides, those corresponding to the general formula OCN--R--COCl inwhich R stands for an aliphatic hydrocarbon group containing more than 6carbon atoms or a cycloaliphatic hydrocarbon group may also be used.Examples of such isocyanatocarboxylic acid chlorides include12-isocyanatododecanoic acid chloride and4-isocyanatocyclohexanecarboxylic acid chloride.

It is also possible to use isocyanatobenzoic acid chlorides which carryinert substituents in the 2-position relative to the isocyanate group.Possible inert substituents are those already mentioned hereinbefore inconnection with the amino phenols.

Isocyanatocarboxylic acid chlorides which contain more than oneisocyanate group or more than one carboxylic acid chloride group arealso suitable. These include, for example, 2,4-diisocyanatobenzoic acidchloride, 2,6-diisocyanatocaproic acid chloride, and2-isocyanatoglutaric acid dichloride. Such compounds containing morethan one isocyanate or chlorocarbonyl group are, however, lesspreferred.

The products of the process according to the invention which carrysilylated carboxylic groups can easily be converted into thecorresponding isocyanato carboxylic acid chlorides by reacting them withchlorination agents such as POCl₃ or SOCl₂.

When the products of the process according to the invention carryingsilylated alcoholic or phenolic hydroxyl groups are used as reactantswith the isocyanatocarboxylic acid chlorides exemplified above (i.e., inthe process for the preparation of polyisocyanates containing estergroups using the above-mentioned products of this process as startingmaterials), the quantity of reactants is generally chosen to provide atleast 0.8 mole of silylated hydroxyl groups for each mole ofchlorocarbonyl groups. The quantities of reactants are preferably chosento provide from 0.8 to 1.2 mole of silylated hydroxyl groups for eachmole of chlorocarbonyl groups. It is particularly preferred to useequimolar quantities (i.e., wherein the molar ratio of the abovementioned reactive groups is 1:1). Although one of the two componentscould be used in an excess outside the range of 0.8 to 1.2 mole, doingso would merely reduce the yield.

The ester-forming reaction is generally carried out within thetemperature range of from 50° to 170° C. The end of the reaction caneasily be detected (if no excess of acid chloride has been used) by thedisappearance of the acid chloride carbonyl band at 1800 cm⁻¹ in theinfrared spectrum.

The ester-forming reaction may be carried out with the aid of suitablecatalysts. Such catalysts are added in quantities of from 0.1 to 10% byweight, preferably from 0.1 to 2% by weight, based on the weight of thereactants. Suitable catalysts include Lewis acids, such as titaniumtrichloride, tin dichloride, and zinc chloride; acids such as sulfuricacid; or bases such as 4-dimethylaminopyridine.

The ester-forming reaction may be carried out with or without a suitablesolvent. Suitable solvents are, for example, diethyl ether, toluene,xylene, chlorobenzene, o-dichlorobenzene, trichloroethylene, ethylacetate, butyl acetate, and any mixtures of such solvents.

The polyisocyanates containing ester groups thereby obtained from theproducts of the process according to the invention are valuable startingmaterials for the preparation of polyurethane plastics. Thecorresponding compounds containing aliphatically or cycloaliphaticallybound isocyanate groups are eminently suitable for the production ofone-component or two-component polyurethane lacquers. The functionalityof the polyisocyanates which contain ester groups may be adapted to theintended use not only by choosing suitable starting materials used fortheir preparation but also by using mixtures of different startingmaterials.

Ester diisocyanates based on aromatic isocyanatocarboxylic acidchlorides and silylated isocyanatophenols occasionally also haveinteresting liquid crystalline properties.

The following examples further illustrate details for the process ofthis invention. The invention, which is set forth in the foregoingdisclosure, is not to be construed or limited either in spirit or inscope by these examples. Those skilled in the art will readilyunderstand that known variations of the conditions of the followingreparative procedures can be used in the process of this invention. Alltemperatures are degrees Celsium unless otherwise noted. All percentagesare percentages by weight.

DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLE 1 Preparation ofO-silylated starting materials

The amino compound containing hydroxyl or carboxyl groups (1 mole) isintroduced into a 500-ml three-necked flask with magnetic stirring bar,internal thermometer, dropping funnel, and reflux condenser, as well aswith bubble counter, drying tube, and gas discharge tube.Hexamethyldisilazane (0.55 mole) is rapidly added dropwise. After theaddition of three drops of trimethylchlorosilane as catalyst, the liquidmixture, which is in some cases heterogeneous, is slowly heated.Evolution of ammonia becomes noticeable at 50° to 55° C. and becomesvery vigorous at 85° to 95° C. for amino alcohols and at 130° C. foramino phenols. The temperature is raised to 140° to 170° C., where it ismaintained until gas evolution ceases (3 to 7 hours). The homogeneousliquid is then purified by rectifying using a mirrored vigreux column.

The method is illustrated by the following compounds:

Example 1.1 4-trimethylsilyloxyphenylamine

Yield: 88.6%

bp: 114°-116° C. (20 mbar)

n_(D) ²⁰ : 1.5189

Example 1.2 3-trimethylsilyloxyphenylamine

Yield: 81%

bp: 115°-116° C. (20 mbar)

Example 1.3 4-trimethylsilyloxybutylamine

Yield: 83%

bp: 63°-64° C. (20 mbar)

IR spectrum: 3380 and 3300 cm⁻¹ (NH stretching vibration), 1600 cm⁻¹ (NHbending vibration)

Elemental analysis (%): Calculated: C, 51.44; H, 11.6; N, 6.0 Found: C,51.40; H, 11.1; N, 5.8

Example 1.4 3-trimethylsilyloxypropylamine

Yield: 75%

bp: 134°-135° C. (495 mbar)

n_(D) ²⁰ : 1.4195

IR spectrum: 3390 and 3340 cm⁻¹ (NH stretching vibration), 1600 cm⁻¹ (NHbending vibration)

¹ H NMR spectrum: 3.45 (t, 2H); 2.55 (t, 2H); 1.45 (m, 2H); 0.85 (s, 2H)ppm

Example 1.5 2-trimethylsilyloxyethylamine

Yield: 83%

bp: 38°-39° C. (20 mbar)

n_(D) ²⁰ : 1.4131

IR spectrum: 3380 and 3300 cm⁻² (NH stretching vibration), 1590 cm⁻² (NHbending vibration)

Example 1.6 2-trimethylsilyloxy-2-methylpropylamine

Yield: 85%

bp: 38°-38.5° C. (20 mbar)

n_(D) ²⁰ : 1.4089

IR spectrum: 3380 and 3280 cm⁻¹ (NH stretching vibration), 1590 cm⁻¹ (NHbending vibration)

Example 1.7 trans-4-trimethylsiloxy-cyclohexylamine

Yield: 88%

bp: 81°-83° C. (20 mbar)

n_(D) ²⁰ : 1.4511

IR spectrum: 3365 and 3280 cm⁻¹

Example 1.8 trimethylsiloxyamine

Yield: 51%

bp: 99°-100° C.

n_(D) ²⁰ : 1.4010

IR spectrum: 3370 and 3280 cm⁻¹

Example 1.9 4-aminobenzoic acid trimethylsilylester

Yield: 91%

bp: 110° C. (0.015 mbar)

mp: 62° C.

IR spectrum: 3370 and 1730 cm⁻¹

Example 1.10 2-methyl-4-trimethylsiloxyphenylamine

Yield: 94%

bp: 121° C. (20 mbar)

IR spectrum: 3460, 3370 and 3280 cm⁻¹

Example 2 Process according to the invention (general method ofpreparation)

4,4-Diisocyanatodiphenylmethane (500 g, 2 mole) is weighed into a 500-mlglass flask equipped with magnetic stirring bar, internal thermometer,dropping funnel and distillation bridge, with a 100 ml nitrogen flask asreceiver. After the diisocyanate compound is melted under argon,trimethylsilyloxyaryl(alkyl)amine (0.4 mole) is slowly introduceddropwise at 110° to 120° C., accompanied by formation of white mists.When all of the amine has been added, the apparatus is carefullyevacuated while being further heated to 200° C. The colorless liquidwhich distills over is then fractionated. The method is illustrated bythe following compounds:

Example 2.1 4-trimethylsilyloxyphenylisocyanate

Yield: 95%

bp: 52°-53° C. (0.24 mbar)

n_(D) ²⁰ : 1.5032

IR spectrum: 2280 cm⁻¹ (N═C═O)

¹ H NMR spectrum: 6.92 (m, 4H); 0.31 (s, 9H) ppm

Elemental analysis (%): Calculated: C, 58.0; H, 6.3; N, 6.8 Found: C,58.4; H, 6.2; N, 7.2

Example 2.2 3-trimethylsilyloxyphenylisocyanate

Yield: 79%

bp: 109° C. (20 mbar)

n_(D) ²⁰ : 1.5025

IR spectrum: 2280 cm⁻¹ (N═C═O)

¹ H NMR spectrum: 6.93 (m, 4H); 0.34 (s, 9H) ppm

Elemental analysis (%): Calculated: C, 58.0; H, 6.3; N, 6.8 Found: C,57.9; H, 6.4; N, 6.7

Example 2.3 4-trimethylsilyloxybutylisocyanate

Yield: 70%

bp: 75°-76° C. (20 mbar)

n_(D) ²⁰ : 1.4250

IR spectrum: 2270 cm⁻¹ (N═C═O)

¹ H NMR spectrum: 3.58 (t, 2H); 3.27 (t, 2H); 1.58 (m, 4H); 0,05 (s, 9H)ppm

Elemental analysis (%): Calculated: C, 51.3 H, 911; N, 7.5 Found: C,50.4; H, 9.0; N, 7.4

Example 2.4 3-trimethylsilyloxypropylisocyanate

Yield: 94%

bp: 68.5°-69° C. (20 mbar)

n_(D) ²⁰ : 1.4200

IR spectrum: 2280 cm⁻¹ (N═C═O)

¹ H NMR spectrum: 3.65 (t, 2H); 3.39 (t, 2H); 1.78 (m, 2H); 0,09 (s, 9H)ppm

Elemental analysis (%): Calculated: C, 48.5; H, 8.7; N, 8.1 Found: C,48.9; H, 9.7; N, 8.2

Example 2.5 2-trimethylsilyloxyethylisocyanate

Yield: 84%

bp: 45° C. (20 mbar)

n_(D) ²⁰ : 1.4140

IR spectrum: 2280 and 2240 cm⁻¹ (N═C═O)

¹ H NMR spectrum: 3.68 (t, 2H); 3.30 (t, 2H); 0.17 (s, 9H) ppm

Elemental analysis (%): Calculated: C, 45.2; H, 8.2; N, 8.8 Found: C,44.7; H, 7.6; N, 8.8

Example 2.6 2-trimethylsilyloxy-2-methylpropylisocyanate

Yield: 96%

bp: 57° C.

n_(D) ²⁰ : 1.4011

IR spectrum: 2260 cm⁻¹ (N═C═O)

¹ H NMR spectrum: 3.40 (s, 2H); 1.22 (s, 6H); 0.12 (s, 2H) ppm

Elemental analysis (%): Calculated: C, 51.3; H, 9.2; N, 7.5 Found: C,51.9; H, 9.3; N, 7.6

Example 2.7 trans-4-trimethylsiloxycyclohexylisocyanate

Yield: 93%

bp: 96°-98° C. (20 mbar)

n_(D) ²⁰ : 1.4492

IR spectrum: 2275 cm⁻¹

Elemental Analysis (%): Calculated: C, 65,3; H, 9,00; 6,57 Found: C,55,9; H, 9,05; N, 6,5

Example 2.8 trimethylsiloxyisocyanate

Yield: 67%

bp: 105° C.

n_(D) ²⁰ : 1.3618

IR spectrum: 2280 cm⁻¹

Example 2.9 4-isocyanatobenzoic acid trimethylsilylester

Yield: 88%

bp: 85° C. (0.03 mbar)

mp: 48° C.

IR spectrum: 2280 and 1730 cm⁻¹

Example 2.10 2-methyl-4-trimethylsiloxyphenylisocyanate

Yield: 90%

bp: 67°-68° C. (0.06 mbar)

n_(D) ²⁰ : 1.5056

IR spectrum: 2280 cm⁻¹

Example 3 Use according to the invention (general method)

Trimethylsilyloxyphenyl-, trimethylsilyloxyethyl- ortrimethylsilyloxybutylisocyanate (4 mole) is introduced into a 25-mlround bottomed flask equipped with magnetic stirring bar,microdistillation bridge, drying tube and receiver. An equivalent molarquantity of 6-isocyanatohexanoic acid chloride or 3-isocyanatopropanoicacid chloride is added by a pipette. The reaction mixture is heated to130° C. and kept at this temperature with stirring until the reaction iscompleted (about 24 hours). The liquid is purified in a bulb-tubedistillation apparatus.

Example 3.1 Use according to the invention as reactant for6-isocyanatocaproic acid chloride

The method is illustrated by the following compounds:

Example 3.1.1 6-isocyanatocaproic acid 4-isocyanatophenyl ester

Yield: 72%

bp: 160°-180° C. (0.37 mbar)

n_(D) ²⁰ : 1.5235

IR spectrum: 2280 cm⁻¹ (N═C═O), 1755 cm⁻¹ (COO)

¹ H NMR spectrum: 7.02 (s, 4H); 3.30 (t, 2H); 2.55 (t, 2H); 1.56 (m, 2H)ppm

Elemental analysis (%): Calculated: C, 61.3; H, 5.1; N, 10.2 Found: C,61.1; H, 5.1; N, 10.6

Example 3.1.2 6-isocyanatocaproic acid 3-isocyanatophenyl ester

Yield: 75%

bp: 170° C. (0.05 mbar)

n_(D) ²⁰ : 1.5240

IR spectrum: 2280 cm⁻¹ (N═C═O), 1755 cm⁻¹ (COO)

¹ H NMR spectrum: 7.03 (m, 4H); 3.24 (t, 2H); 2.42 (t, 2H); 1.59 (m, 6H)ppm

Elemental analysis (%): Calculated: C, 61.3; H, 5.1; N, 10.2 Found: C,61.4; H, 5.2; N, 10.3

Example 3.1.3 6-isocyanatocaproic acid 4-isocyanatobutyl ester

Yield: 85%

bp: 165°-170° C. (0.07 mbar)

n_(D) ²⁰ : 1.4620

IR spectrum: 2280 cm⁻¹ (N═C═O), 1735 cm⁻¹ (COO)

¹ H NMR spectrum: 4.09 (t, 2H); 3.34 (t, 4H); 2.32 (t, 2H); 1.63 (m,10H) ppm

Elemental analysis (%): Calculated: C, 56.7; H, 7.1; N, 11.0 Found: C,56.8; 7.0; N, 11.3

Example 3.1.4 6-isocyanatocaproic acid 2-isocyanatoethyl ester

Yield: 31%

bp: 150°-160° C. (0.1 mbar)

IR spectrum: 2280 cm⁻¹ (N═C═O), 1735 cm⁻¹ (COO)

¹ H NMR spectrum: 4.19 (t, 2H); 3.50 (t, 2H); 3.30 (t, 2H); 2.38 (t,2H); 1.57 (m, 6H) ppm

Example 3.2 Use according to the invention as reactant for3-isocyanatopropionic acid chloride

The method is illustrated by the following compounds:

Example 3.2.1 3-isocyanatopropionic acid 4-isocyanatophenyl ester

Yield: 70%

bp: 160° C. (0.04 mbar)

n_(D) ²⁰ : 1.5377

IR spectrum: 2270 cm⁻¹ (N═C═O), 1750 cm⁻¹ (CO)

¹ N NMR spectrum: 7.50 (s, 4H); 3.63 (t, 2H); 2.79 (t, 2H) ppm

Elemental analysis (%): Calculated: C, 56.4; H, 4.2; N, 12.0 Found: C,56.9; H, 3.7; N, 12.1

Example 3.2.2 3-isocyanatopropionic acid 3-isocyanatophenyl ester

Yield: 72%

bp: 150°-190° C. (0.03 mbar)

mp: 45°-46° C.

IR spectrum: 2285 cm⁻¹ (N═C═O), 1760 cm⁻¹ (COO)

¹ H NMR spectrum: 7.32 (m, 2H); 6.97 (m, 2H); 3.73 (t, 2H); 2.86 (t, 2H)ppm

Elemental analysis (%): Calculated: C, 56.4; H, 3.4; N, 12.0 Found: C,56.7; H, 3.8; N, 11.8

Example 3.2.3 3-isocyanatopropionic acid 4-isocyanatobutyl ester

Yield: 60%

bp: 150°-170° C. (0.05 mbar)

n_(D) ²⁰ : 1.4598

IR spectrum: 2280 cm⁻¹ (N═C═O), 1735 cm⁻¹ (COO)

¹ H NMR spectrum: 4.18 (5, 2H); 3.46 (m, 4H); 2.60 (t, 2H); 1.71 (t, 4H)ppm

Elemental analysis (%): Calculated: C, 50.9; H, 5.7; N, 13.2 Found: C,50.8; H, 6.0; N, 13.4

Example 3.3 Use according to the invention as reactant for4-isocyanatobenzoyl chloride and 3-isocyanatobenzoyl chloride

The general method of Example 3 is modified in that 10 ml ofo-dichlorobenzene is used as solvent and the reaction mixture is heatedat 165° C. to the end of the reaction in the presence of 0.1% catalyst.After the solvent has been drawn off, the products are purified bydistillation in a bulb-tube distillation apparatus. The method isillustrated by the compounds in the following table.

    __________________________________________________________________________                                   Heating                                                                       temperature                                                                   for bulb-tube                                                                            Melting    Elemental                                               distillation                                                                         Yield                                                                             point                                                                              IR-bands.sup.2                                                                      analysis (%)             No.                                                                              Diisoyanate            Catalyst                                                                           °C.                                                                           %   (°C.)                                                                       (cm.sup.-1)                                                                         Calculated                                                                          Found              __________________________________________________________________________    3.3.1                                                                             ##STR3##              TiCl.sub.3                                                                         180-200                                                                              68  K 117, 5 n 150                                                                     2320, 1740                                                                          C: 64.3 H: 2.9 N:                                                             10.0  64.4 2.9 10.0      3.3.2                                                                             ##STR4##              TiCl.sub.3                                                                         180    90  K 91, 8 i                                                                          2300, 1745                                                                          C: 64.3 H: 2.9 N:                                                             10.0  64.5 2.9 10.0      3.3.3                                                                             ##STR5##              ZnCl.sub.2                                                                         190    30  K 106 i                                                                            2310, 1740                                                                          C: 64.3 H: 2.9 N:                                                             10.0  64.4 10.0          3.3.4                                                                             ##STR6##              TiCl.sub.3 TiCl.sub.4 H.sub.2 SO.sub.4 ZnCl.sub.                              2 DMAP.sup.1                                                                       150-160                                                                              86 75 80 36 50                                                                    K 69 i                                                                             2280, 1745                                                                          C: 64.3 H: 2.9 N:                                                             10.0  64.4 3.0           __________________________________________________________________________                                                               10.1                .sup.1 4-dimethylamino-pyridine                                               .sup.2 K = crystalline,                                                       n = nematic,                                                                  i = isotropic                                                            

Example 4 Use according to the invention

Following the general method of Example 3 the diisocyanates 4.1 through4.3 as set forth in the following table are made.

    __________________________________________________________________________                                  heating tempe-                                                                rature for bulb                                                                           Melting                                                           distillation                                                                          Yield                                                                             point                                                                              IR-bands                                                                            Elemental analysis       No.                                                                              Diisocyanate           Cat.                                                                              (°C.)                                                                          %   (°C.)                                                                       in cm.sup.-1                                                                        Calculated                                                                          found              __________________________________________________________________________    4.1                                                                               ##STR7##              H.sub.2 SO.sub.4                                                                  180     95  K 81 a.sup.1 73                                                                    2300, 1740                                                                          C: 65.31 H: 3.43 N:                                                           9.52  65.6 3.6 9.6       4.2                                                                               ##STR8##              H.sub.2 SO.sub.4                                                                  180     92  K 71.5 a 66 i                                                                      2280, 1725                                                                          C: 65.31 H: 3.43 N:                                                           9.52  65.7 3.5 9.7       4.3                                                                               ##STR9##              TiCl.sub.4                                                                        160     20  K 66 a 14 i                                                                        2280, 1710                                                                          C: 63.99 H: 5.37 N:                                                           9.32  63.7 5.6           __________________________________________________________________________                                                               9.4                 .sup.1 a = anisotropic                                                   

Although the invention has been described in detail in the foregoing forthe purpose of illustration, it is to be understood that such detail issolely for that purpose and that variations can be made therein by thoseskilled in the art without departing from the spirit and scope of theinvention except as it may be limited by the claims.

What is claimed is:
 1. A process for the preparation of an isocyanate compound substituted with one or more silylated hydroxyl groups of silylated carboxyl groups comprising heating in a temperature range of from about 20° C. to about 300° C., a mixture of(i) an amine precursor corresponding to said isocyanate compound substituted with one or more silylated hydroxyl groups or silylated carboxyl groups, and (ii) at least one to about 20 molar quantities of an organic polyisocyanate that is essentially non-volatile under the conditions of said process.
 2. A process according to claim 1 wherein the temperature range is from about 20° C. to about 200° C.
 3. A process according to claim 1 wherein the temperature is initially about 100° C. to about 140° C. and is subsequently raised to about 200° C.
 4. A process according to claim 1 wherein the process is carried out at a pressure at or below atmospheric pressure.
 5. A process according to claim 1 wherein the amine precursor has the formula ##STR10## wherein m is zero or an integer of from 2 to
 4. 6. A process according to claim 1 wherein the essentially non-volatile organic polyisocyanate is a diphenylmethane diisocyanate.
 7. A process according to claim 1 wherein the essentially non-volatile organic polyisocyanate is one or more compounds selected from the group consisting of 4,4'-diisocyanatodiphenylmethane, 2,4'-diisocyanatodiphenylmethane, and 2,2'-diisocyanatodiphenylmethane.
 8. A process according to claim 1 for the preparation of an isocyanate compound substituted with a silylated alcoholic or phenolic hydroxyl group comprising heating in a temperature range of from about 20° C. to about 200° C., at a pressure at or below atmospheric pressure, a mixture of(i) an amine precursor having the formula ##STR11## wherein m is an integer of from 2 to 4, and (ii) at least about one to about 20 molar quantities of one or more compounds selected from the group consisting of 4,4'-diisocyanatodiphenylmethane, 2,4'-diisocyanatodiphenylmethane, and 2,2'-diisocyanatodiphenylmethane. 